Tuesday, December 5, 2017
4:00 pm
South Mudd 365

The Dix Planetary Science Seminar

Planet Formation Puzzles Near and Far
Sarah Millholland, Astronomy Department, Yale University

This talk will tour a variety of problems in planetary dynamics in the Solar System and beyond, starting with nearby systems and getting progressively more expansive. I will review previous work to constrain the orbit of Planet Nine and detail our recent efforts to explain the 98 degree obliquity of Uranus with a secular spin orbit resonance that may have been traversed as the initially highly eccentric orbit of Planet Nine was circularized. (Spoiler: it doesn't work!) Moving beyond the Solar System, I will turn to focus on the nearest and most dynamically rich multi-planet system: Gliese 876. I will present new dynamical constraints obtained using hundreds of new RV measurements. The system is deeper in the three-body resonance and less chaotic than previously thought, which holds important clues to the system's primordial formation. Furthermore, I will present puzzling observations of chaos in the Gliese 876 planets, with implications for understanding chaos present in other planetary systems as well. Finally, expanding even further, I will discuss our recent work that shows that the prototypical Kepler multi-planet system tends to host planets with nearly uniform masses and radii.

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